In the two months since the launch of Sword Art Online, over 2000 players died as a result of Akihiko Kayaba trapping them in the game, yet no one has been able to defeat, or even locate, the boss of the first floor's labyrinth.
On December 2, 2022, a player named Diavel calls a group of players, including Kirito, together to form a raiding group, having found the boss's chamber. As players form into parties in preparation of the raid, Kirito forms a party with a young girl named Asuna.
During the meeting, a player named Kibaou suddenly places blame for the deaths of the other players on beta testers currently logged in, claiming that they had prior knowledge of the game but refused to share this information or aid newer players, demanding compensation in exchange for their lives. Another player, Agil, defuses the situation by pointing out that the beta testers did share their knowledge in the form of an in-game guide book, available to all players for free. The same guide book has information on the first floor's boss: Illfang the Kobold Lord. The boss is aided by Kobold Sentinel minions and armed with a large axe and a shield, but when its HP are reduced to one bar, he discards his axe to brandish a talwar. With this information in hand, the raiding party decides to leave the following morning to fight the boss.
That evening, Kirito and Asuna share bread smattered with cream that Kirito got in an early quest. Asuna tells Kirito that she came to this town because it would be better than cowering in the game's starting hub town, and that even if she dies, she would not lose to this game.
The next day, the raiding party makes way for Illfang's chamber. The battle goes well at first, and when Illfang's HP is reduced to one bar, Diavel tells the other raiders to fall back so he can finish it off. However, Kirito suddenly notices that, instead of a talwar, Illfang now uses a nodachi, which completely changes its attack patterns.
Diavel is fatally hit by Illfang. When Kirito offers a healing potion, Diavel rejects it. Kirito then realizes that Diavel is a fellow beta tester: he intended to get the Last Attack bonus on the boss so he could get an extra reward. With his dying breath, Diavel begs Kirito to defeat the boss.
With Diavel dead, Kirito and Asuna step up to challenge Illfang. In spite of Illfang's overwhelming speed, the duo is able to evade his attacks. Together, Kirito and Asuna attack Illfang until Kirito lands the final blow upon the Kobold Lord and destroys it, clearing the first floor and earning the Coat of Midnight as his Last Attack reward.
The raiding party celebrates their victory, but Kibaou suddenly accuses Kirito of letting Diavel die because he withheld information about the boss. Distrust begins to spread among the raiding party, as anyone could be a beta tester. Kirito, realizing that this could cause backlash against any beta testers playing the game, suddenly proclaims to be better than any other beta tester, boasting that he made it farther than the other testers and knew more about the game than any other player. Kibaou and many other raiders go on to accuse Kirito of being a cheater, or worse still, a "Beater" (a portmanteau of "beta tester" and "cheater").
Equipping his new Coat of Midnight, Kirito leaves, cautioning Asuna to find a guild she can trust since there are limits to how much a solo player can do. He disbands the party with Asuna, and walks away.
Tropes in this episode include:
- Bittersweet Ending: Illfang has been defeated, but Kirito is forced to isolate himself from the other players and Diavel is dead.
- First Girl Wins: Asuna is the first girl Kirito meets.
- Screw This, I'm Outta Here!: Kirito leaves the raiding group behind at the end of the episode.
- Talking Is a Free Action: After Diavel is wounded, he and Kirito talk about the situation while everybody else — including Illfang — is frozen.
- What the Hell, Hero?: Kibaou calls Kirito out for withholding information from the boss.